Health and Happiness

Last week Anna woke up from her nap in respiratory distress, a barking cough, that apparently hurt because she sat up crying. Through her sobs I deciphered, "But I wanted to be happy !" It seemed to me that she was equating feeling good, being healthy, with happiness...   is so, she will find herself "not happy" a lot on her road of life. How does a parent teach a child to be happy despite their lack of health? It sounds like a case for God's grace, for only saints seem to have thrived in this state, finding their joy in God and offering their suffering to Him.